Relative mode testing

 =====================

 See test program at the bottom of this file.

 Initial tests:

  - When in relative mode, the mouse shouldn't be moveable outside of the window.

  - When the cursor is outside the window when relative mode is enabled, mouse

    clicks should not go to whatever app was under the cursor previously.

  - When alt/cmd-tabbing between a relative mode app and another app, clicks when

    in the relative mode app should also not go to whatever app was under the

    cursor previously.

 Code

 ====

     #include <SDL.h>

     int PollEvents()

     {

         SDL_Event event;

         while (SDL_PollEvent(&event))

         {

             switch (event.type)

             {

                 case SDL_QUIT:

                     return 1;

                 default:

                     break;

             }

         }

         return 0;

     }

     int main(int argc, char *argv[])

     {

         SDL_Window *win;

         SDL_Init(SDL_INIT_VIDEO);

         win = SDL_CreateWindow("Test", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 800, 600, 0);

         SDL_SetRelativeMouseMode(SDL_TRUE);

         while (1)

         {

             if (PollEvents())

                 break;

         }

         SDL_DestroyWindow(win);

         SDL_Quit();

         return 0;

     }